1. Field of the Invention
The present invention relates to an improved injection molding machine apparatus and method in which the moving platen is configured to perform (i) molten material injection actuation and (ii) molded article ejection actuation.
2. Description of Related Art
Coinjection molding is typically used to mold multi-layered plastic packaging articles having a laminated wall structure. Each layer is typically passed through a different annular or circular passageway in a single nozzle structure and each layer is partially, sequentially, injected through the same gate. Some coinjection molding systems include a moving platen assembly which is coupled to a second hot runner shooting pot injection unit in addition to an ejector plate mechanism. See, for example, the following:                U.S. patent application Ser. No. 10/879,575 entitled APPARATUS AND METHOD FOR ACTUATION OF INJECTION MOLDING, SHOOTING POTS;        U.S. patent application Ser. No. 10/879,576 entitled INJECTION MOLDING MACHINE SHOOTING POT WITH INTEGRAL CHECK VALVE;        U.S. patent application Ser. No. 10/879,581 entitled INJECTION MOLDING MACHINE SPIGOTTED SHOOTING POT PISTON;        U.S. patent application Ser. No. 10/879,621 entitled APPARATUS AND METHOD FOR SEALING INJECTION UNIT AND SPRUE;        U.S. patent application Ser. No. 10/879,582 entitled CONTROL SYSTEM FOR A DYNAMIC FEED COINJECTION PROCESS;        U.S. patent application Ser. No. 10/880,494 entitled HOT RUNNER COINJECTION NOZZLE WITH THERMALLY SEPARATED MELT CHANNELS;        U.S. patent application Ser. No. 10/880,493 entitled COINJECTION MOLDING COOLED SHOOTING POT CYLINDER; and        U.S. patent application Ser. No. 10/887,353 entitled APPARATUS AND METHOD FOR INJECTION MOLDING SHOOTING POT WEDGE FEATURE.However, none of the above U.S. patent documents provides a molding system in which the molten material injection functions and molded article ejection functions are advantageously combined in a time and space efficient manner.        
U.S. Pat. Nos. 6,152,721 and 6,540,496 to Schad both disclose a coinjection molding machine having an injection actuation mechanism attached to the stationary platen that operates injector rods that pass through the stationary platen to actuate hot runner shooting pots in the mold. There is no disclosure of how the hot runner shooting pot actuation and a molded part ejection actuation could be configured from the machine's moving platen side.
Thus, what is needed is an injection molding method and apparatus in which both a molten material injection function and a molded part ejection function are operated from a moving platen side of the injection molding machine. This conserves space in the machine's footprint by co-locating driving structure, and reduces cycle time by using the movement of the moving platen to enhance injection and ejection.